| Rivers are the main channel of transportation from land to marine, which have a great impact on the watershed and marine environment and are the regions of interaction studied of the land and sea. Sediments is a mixture of table watershed weathering products, which can not only reflect weathering characteristics of source, but also reflects homogenization trend of the migration process. Therefore, sediments is significant study object of recognizing super-gene geological processes. Clay minerals are the main mineral components of fine-grained sediments. As the products of rock weathering, clay minerals are widely distributed on the ground, and they are the main source of fine-grained sediments of rivers. Due to its unique physical and chemical properties, clay minerals are sensitive to the changes of the geological environment.Qiantang River, located in subtropical monsoon climate zone, is a single river flowing into the sea of the southeast coastal region. The characteristics of sediments are distinctly different, due to extremely complex hydrodynamic conditions and topography. So studying the composition and spatial distribution characteristics of modern sediments of different sections and main tributaries River is of great significance to clarify the river sedimentation and the source-sink relationship between the main stream and tributaries.In this paper, clay minerals (<2μm) XRD and Ph, Eh of 159 samples have been tested. Afterwards, together with the experimental results, the features and influencing factors of clay minerals and main tributaries of sediments on the Qiantang River have been studied. Furthermore, the source-sink relationship between arterial and tributary of the Qiantang River have been preliminary studied.The analysis of clay minerals in the deposits shows that almost all samples contain illite (I), kaolinite (K), chlorite (Ch), vermiculite (V) and 1.4nm transitional mineral (HIV) and smectite (S). On the type of clay mineral assemblages, Xin’an River, Fuchun River and tributaries in the basin mainly belong to type 1:illite-kaolinite-vermiculite-chlorite-smectite; Qiantang River mainly belong to type 2: illite-kaolinite-chlorite-vermiculite-smectite; Hangzhou Bay mainly belong to type 3:illite-kaolinite-chlorite-smectite-vermiculite. The Xin’an River, Fuchun River and their tributary have contain 1.4nm transitional minerals in the sediments, not do the Qiantang Rive and Hangzhou Bay.The study find that the difference among the different river branches of the mainstream of Qiantang River is as follows:from upstream to downstream, the average content of illite, chlorite and smectite increases gradually, kaolinite and vermiculite average content gradually reduced. Clay minerals in sediments was also quite different between high tidal flat and central tidal flat:the average contents of illite and smectite in the high tidal flat were higher than which of the central tidal flat; while the average contents of kaolinite, chlorite and vermiculite (containing 1.4nm transitional mineral) in the central tidal flat were higher than which of the high tidal flat.Research shows that clay mineral assemblages and distribution characteristics of sediments in the mainstream are mainly affected by provenance:Q cluster analysis of clay minerals in sediments of the mainstream and the main tributary of study area is conducted, combined with the clay mineral triangular end metagraph and the pie chart of the average content of clay minerals in each reach to compare clay minerals of different reaches. The results show that Xinan River and Fuchun Rive are similar with the main tributariesof basin; Hangzhou Bay substances are largely influenced by the Yangtze River; Qiantang River sediments are contributed to clay minerals in the basin and the foreign material brought by downstream. Hydrodynamic conditions and the medium environment are the secondary influencing factors, and the clay minerals are merely affected by sedimentary differentiation. |
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